Fuel supply system



IN V EN TOR.

ATTORN E Y.

Oct. 31, 1961 F. BARFOD FUEL SUPPLY SYSTEM Filed Feb. 17, 1960 FREDER/KBARFOD.

United States Patent 3,006,326 FUEL SUPPLY SYSTEM Frederik Barfod,Detroit, Mich., assignor to The Bendix Corporation, a corporation ofDelaware Filed Feb. 17, 1960, Ser. No. 9,291 3 Claims. (Cl. 123-119) Thepresent invention relates to fuel supply systems for internal combustionengines having an induction passage pressure responsive control forvarying the quantity of fuel supplied to the engine and moreparticularly to temperature and air flow responsive means for varyingthe induction passage pressure applied to the control.

A fuel supply system for which the present invention is particularlyadapted, is disclosed and claimed in my copending application Serial No.604,483 filed August 16, 1956, now Patent No. 2,930,370, granted Mar.29, 1960.

It is an object of the present invention to provide in a fuel supplysystem means for enriching the fuel-air mixture supplied to the engineduring starting and warmup operation.

Other objects and advantages of the invention will become readilyapparent from the following description taken in connection with theaccompanying drawing wherein:

FIGURE 1 shows a schematic view of a fuel supply system embodying thepresent invention; and

FIGURE 2 is a sectional view taken along lines 2-2 of FIGURE 1.

Referring now to the drawings numeral designates a fuel supply systemfor supplying fuel to an internal combustion engine 12 which has aninduction passage 14 with a throttle 16 mounted therein. Fuel supplysystem 10 is provided with a housing 18 having an inlet 20 which isadapted to be connected to a source of fuel (not shown) through anappropriate conduit. A pump 22 is mounted in the housing for connectionwith inlet 20. Appropriate means (not shown) may be provided to rotatepump 22 as a function of engine speed. Also mounted in said housing is adistributor valve 24 adapted to be rotated as a function of engine speedby appropriate means (not shown). Valve 24 is provided with a port 26located in the side wall thereof which is arranged for successiveregistration with a plurality of ports 28 formed in the housing 18. Thenumber of ports 28 may conveniently correspond to the number ofcylinders in the engine with which the fuel supply system is associated.Each port 28 opens into a discharge conduit 30 having a nozzle 32secured to one end thereof. The nozzles 32, only one of which is shown,are adapted to inject fuel into the intake manifold of the engine, thenumber of nozzles may be equal to or less than the number of cylindersof the engine depending on the construction of the intake manifold. Theflow through port 26 is controlled by a piston 34 which is mounted foraxial movement within valve 24. Piston 34 is responsive to differencesin pressure between the pressures in chambers 36 and 38 locatedrespectively on opposite sides of said piston. Fuel is supplied tochamber 36 from pump 22 via conduit 40 and metering restriction 42. Fuelis supplied to chamber 38 from pump 22 via conduit 40, valve 44 andconduit 46. Chamber 38 is connected to inlet 20 via conduit 46 andrestriction 48. A housing 50 projects from the main housing 18 andcontains a movable wall 52 which divides the interior of housing 50 intochambers 54 and 56. Movable wall 52 is operatively connected to valve44. A spring 58 is mounted in chamber 54 to urge movable wall 52 in adirection to close valve -44. A vent 60 is provided in the side wall ofhousing 50 to connect chamber 56 to the atmosphere.

The induction passage 14 is provided with a port 62 Patented Oct. 31,196] downstream of the throttle valve 16. A conduit 64 connects port 62to chamber 54. The movable wall 52 is moved in response to the pressurediflerential between the pressures in chambers 54 and 56 Le. atmosphericpressure and induction passage pressure, to urge Valve 44 toward openposition.

An unbalanced air valve 66 is mounted in induction passage 14 on a shaft68. Air valve 66 is unbalanced so as to be opened by air flow throughthe induction passage 14. An air valve lever 70 is secured to shaft 66and is provided at its free end with a pin 72 for engagement with thehooked end of a thermostat 74 which is mounted in a housing on the sideof the induction passage 14. The thermostat 74 is exposed to atemperature indicative of engine temperature either directly, by passingheated air through the housing or through the use of an electric heatingcoil having predetermined characteristics.

In operation, fuel is supplied at substantially constant pressure toinlet 20 from whence it flows to pump 22 where the pressure is increasedas a function of engine speed. The pressure of fuel in chamber 36 variesas a function of engine speed and acts against an end face of piston 34to urge the piston in a direction to increase the fuel flow through port26. The pressure of fuel in chamber 38 varies as a function of enginespeed and induction passage pressure and acts against an opposite endface of piston 34 to urge the piston in a direction to decrease fuelflow through the port 26. Piston 34 seeks a position to balance thepressures in chambers 36 and 38 and is movable in response to momentarychanges in the pressures in either chamber which may be caused bychanges in engine speed or induction passage pressure. When the valve 44is closed the entire output of pump 22 is delivered to the enginethrough port 26. As the valve 44 is opened a portion of the fueldelivered by pump 22 is by-passed to the inlet 20. The valve 44 is urgedtoward closed position by spring 58 and toward opened position by areduction in induction passage pressure in chamber 54.

Air valve 66 is disposed in the induction passage downstream of port 62so that when the air valve 66 is closed the induction passage pressurecommunicated to chamber 54 is higher than the induction passage pressuredownstream of the air valve and may approach substantially ambient oratmospheric pressure and thus spring 58 is effective to close valve 44causing an enriched mixture to be supplied to the engine. Air valve 66is urged toward closed position by thermostat 74 when the thermostat iscold. As the thermostat 74 warms up the force urging air valve 66towards closed position is reduced. Air valve 66 is urged toward openposition by air flow through the induction passage 14. Thus while thethermostat is cold the position of air valve 66 will be determined bythe balance of forces acting thereon viz., the force of the thermostattending to urge it closed and the air flow acting thereon to urge itopen. During the starting operation of the engine with the thermostatcold the air valve 66 will be substantially closed and thus the valve 44will be substantially closed to provide enriched fuel/ air mixture tothe engine. As the engine starts and during the warmup operation of theengine the air valve 66 will be partially opened by air flow actingthereon so as to modify the induction passage pressure communicated tochamber 54 so as to continue supplying an enriched fuel/ air mixture.When the engine is fully warmed up and operating the air valve 66 is insubstantially wide open position and has little or no effect on theinduction passage pressure communicated to chamber 54.

While I have described my invention in its preferred form it will beunderstood by those skilled in the art that changes in construction fromthat disclosed may be made Without departing from the underlyingprinciples of the invention.

I claim:

1. A fuel supply system for an internal combustion engine having asource of fuel and an induction passage with a throttle thereincomprising a conduit adapted'to connect said source with said engine, apump in said conduit, a by-pass connected to said conduit on either sideof said pump, a valve controlling the flow through said by-pass, ahousing, a movable wall in said housing operatively connected to saidvalve and dividing the interior of said housing into first and secondchambers, means venting said first chamber to the atmosphere, a port insaid induction passage downstream of said throttle, passage meansconnecting said port to said second chamber, resilient means in saidsecond chamber urging said wall in a direction to close said valve, anunbalanced air valve mounted in said induction passage downstream ofsaid port, said air valve being urged toward open position in responseto air flow through said induction passage and a thermostat operativelyconnected tosaid air valve for urging said air valve toward closedposition.

2. A fuel supply system for an internal combustion engine having asource of fuel and an induction passage with a throttle therein,comprising a fuel meteringdevice adapted for connection to said sourceand to said engine for delivering metered fuel to said engine, meansresponsive to induction passage pressure operatively connected to saiddevice for controlling the quantity of fuel supplied to the engine, aport in said induction passage downstream of said throttle, a conduitconnecting said port to said first mentionedrmeans, an unbalanced airvalve openable in response to air flow mounted in said induction passagemeans downstream of said port and temperature responsive means urgingsaid air valve toward closed position.

3. A fuel supply system for an internal combustion engine having asource of fuel and an induction passage with a throttle thereincomprising a fuel metering device adapted to supply fuel from saidsource to said engine,

'means operatively connected to said device for controlling the quantityof fuel supplied by said device to the engine, a movable walloperatively connected to said first mentioned means, resilient meansurging said wall in direction to move said first mentioned means in afuel supply increasing direction, an unbalanced air valve in saidinduction passage downstream of said throttle, means for subjecting saidwall to the pressure in said induction passage between said throttle andair valve to urge said wall in a direction to decrease the fuel supplyto the engine, and means responsive to a temperature indicative ofengine temperature for urging said air valve toward closed position.

No references cited.

